2 story x brace brace beam design

[carnahanad]

Hello,

Do I still design the beam at the center of the 2 story X for the moment and axial forces that result from the tension and 0.3compression as described in AISC 341-05 section 13.4a if I'm designing 2 story Xs? I was making the top and bottom of the X braces the same size to try and make the difference in strength at the center small. The tension would cancel out and the compression would be the difference due to the length of the braces which should be relatively small. Is this the right path?

Thanks,
Alex

 

[sdz]

If the tension cancels out the why doesn't the compression? While the intermediate beam might theoretically carry very small loads you should design for lateral strength and stiffness to ensure the bracing is restrained.

 

[sandman21]

No the .3Pu is for chevron brace, however the beam still needs to be designed for the unbalanced load between the tension and compression, moments that occur and axial load.